It has been proposed to incorporate certain furenidones, i.e. 4 .hydroxy-2,3-dihydrofuran-3-ones with two alkyl substituents in the 2- and 5-positions, into foodstuffs in order to improve their flavouring properties. It was found, however, that these compounds are not quite stable under certain conditions. The problem arises particularly when foodstuffs containing the furenidone, in particular a 2,5-dialkylfurenidone, are stored for a prolonged time or when heating when preparing the foodstuff is necessary.